Department of Obstetrics and Gynecology, University of Colorado Denver/Anschutz Medical Campus, Aurora, CO 80045, USA.
Semin Perinatol. 2011 Oct;35(5):262-9. doi: 10.1053/j.semperi.2011.05.009.
Intrauterine growth restriction (IUGR) is commonly defined as an estimated fetal weight of less than the 10th percentile. While 70% of these are small for normal reasons and not at risk, 30% are pathologically small at risk for numerous complications including fetal death. In the late preterm IUGR fetus (>34 weeks), prematurity risks less and the risk of fetal demise becomes the primary concern. Pulsed-wave Doppler interrogation of the umbilical and middle cerebral artery is useful in reducing perinatal mortality, however, Doppler changes in these vessels of the IUGR fetus may not occur after 34 weeks gestation. There are no randomized trials addressing the timing of delivery of the IUGR fetus in the late preterm or early-term period. However, retrospective reports show an increase risk of fetal demise. While timing the delivery of the late preterm/early-term IUGR fetus requires consideration of multiple factors (e.g. degree of growth restriction, etiology, amniotic fluid volume, and biophysical and Doppler testing), available data suggests that delivery should occur by 37 to 38 weeks for singleton IUGR fetuses. In twin pregnancies with a co-twin IUGR fetus, chorionicity also impacts timing of delivery, but delivery should occur by 34-36 weeks.
宫内生长受限（IUGR）通常定义为估计胎儿体重低于第 10 百分位数。虽然其中 70%是由于正常原因而相对较小，并不存在风险，但 30%是病理性的，存在多种并发症的风险，包括胎儿死亡。在晚期早产儿 IUGR 胎儿（>34 周）中，早产风险较小，胎儿死亡风险成为主要关注点。对脐动脉和大脑中动脉的脉冲波多普勒检查有助于降低围产期死亡率，然而，34 周妊娠后这些 IUGR 胎儿血管的多普勒变化可能不会发生。目前尚无关于晚期早产或足月期 IUGR 胎儿分娩时机的随机试验。然而，回顾性报告显示，胎儿死亡风险增加。虽然需要考虑多种因素来确定晚期早产/足月 IUGR 胎儿的分娩时机（例如生长受限的程度、病因、羊水体积以及生物物理和多普勒检查），但现有数据表明，对于单胎 IUGR 胎儿，应在 37 至 38 周分娩。对于有伴同胎 IUGR 胎儿的双胎妊娠，绒毛膜性也会影响分娩时机，但应在 34-36 周分娩。
